Apparatus and method for extracting organic compounds from plant material using carbon dioxide

ABSTRACT

An apparatus for extracting organic compounds from plant materials using subcritical or supercritical carbon dioxide is described. The apparatus has a sealable pressure chamber into which carbon dioxide dry ice and the plant materials are inserted, the pressure chamber, once sealed, self-pressurizing as the container and contents are warmed to a chosen temperature, converting the solid CO 2  to liquid, or to a super-critical fluid as the temperature and pressure are raised above the Critical Point. The chamber can be rotated when subcritical CO 2  liquid is employed to improve mixing between the liquid and the plant material. After a suitable extraction time, the carbon dioxide solvent containing the extracted material is directed into a separator such that the carbon dioxide and extracted material can be effectively separated, thereby avoiding significant quantities of viscous and waxy extracted materials remaining in the chamber and valves after the carbon dioxide solvent is warmed and allowed to exit the chamber.

RELATED CASES

The present application claims the benefit of Provisional PatentApplication Ser. No. 62/106,028, filed on Jan. 21, 2015, and entitled“Apparatus and Method for Extracting Organic Compounds from PlantMaterial Using Carbon Dioxide” by Lisa F. Kinney et al., whichapplication is hereby incorporated by reference herein for all that itdiscloses and teaches.

FIELD OF THE INVENTION

The present invention relates generally to extracting organic compoundsfrom plant material and, more particularly, to extracting organiccompounds from plant material using supercritical carbon dioxide orsubcritical carbon dioxide liquid generated from dry ice in a sealedcontainer, and separating the dissolved compounds from the carbondioxide outside the chamber.

BACKGROUND

Essential oils and other desirable or useful materials found inbotanicals including herbs, fruits, flowers, leaves, skins, stems,stalks, roots, seeds, nuts and berries, have historically been extractedusing organic solvents, steam distillation, and/or pressing. Forexample, butane hash oil (BHO) is the essential oil from the cannabisplant extracted using n-Butane as a solvent and a vacuum oven. Each ofthese extraction methods has undesirable features: for example,incomplete extraction; the necessity of expensive, toxic, caustic, orflammable solvents having significant disposal costs; damage to theextracted constituents from heat; the inability to specifically targetdesired for constituents for extraction; difficulty in obtainingsolvents for home or small business use; and the need for expertpersonnel and complex apparatus for performing extractions. Additionallyuse of extraction solvents such as propane, butane, pentane and hexane,or mixtures of alcohols requires processing beyond the extractionprocess in order to ensure that the extracted materials are safe for useor consumption.

More recently, supercritical liquids have been used for extractingbotanicals, largely alleviating problems associated with heating, theneed for expensive, toxic, caustic or flammable solvents havingsignificant disposal costs, solvent availability, and the need forexpert personnel. Extractions using subcritical/supercritical carbondioxide have the advantage that CO₂ is non-toxic; non-flammable;operates around room temperature; inexpensive; and environmentallyfriendly. Further, the extraction efficiency of carbon dioxide forcertain compounds may be adjusted by increasing or decreasing pressuresand/or temperatures of the carbon dioxide, thereby permittingextractions having varying levels of certain compounds. For example,concentrations of less-desirable plant constituents, such aschlorophyll, can be reduced without secondary processing, by choosingconditions which reduce their solubility in subcritical or supercriticalcarbon dioxide.

SUMMARY OF THE INVENTION

Embodiments of the present invention overcome the disadvantages andlimitations of the prior art by providing an apparatus and method forselectively extracting organic compounds from plant material.

Another object of embodiments of the invention is to provide anapparatus and method for extracting organic compounds from plantmaterial without the need for caustic and flammable solvents, andcomplex apparatus.

Additional objects, advantages and novel features of the invention willbe set forth in part in the description which follows, and in part willbecome apparent to those skilled in the art upon examination of thefollowing or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and attained by means ofthe instrumentalities and combinations particularly pointed out in theappended claims.

To achieve the foregoing and other objects, and in accordance with thepurposes of the present invention, as embodied and broadly describedherein, the apparatus for extracting organic compounds from plantmaterial, hereof includes: a chamber adapted for receiving solid carbondioxide, and having an opening; a removable cover for providing agas-tight seal for the opening; a heating element adapted for warmingthe chamber; a porous container adapted to be placed in the chamber forholding the plant material and permitting the plant material to becontacted by subcritical and supercritical carbon dioxide; a manual ventvalve for permitting gases to exit the chamber; a valve for permittingsupercritical and subcritical carbon dioxide containing extractedorganic compounds to exit the chamber, and a separator for receivingsupercritical and subcritical carbon dioxide containing extractedorganic compounds from the chamber and for separating the extractedorganic compounds from the supercritical and subcritical carbon dioxide.

Benefits and advantages of embodiments of the present invention include,but are not limited to, providing an apparatus for extracting organiccompounds from biomaterial without requiring flammable solvents, andwherein the extracted compounds are readily collected from the pressurechamber.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthe specification, illustrate the embodiments of the present inventionand, together with the description, serve to explain the principles ofthe invention. In the drawings:

FIG. 1 is a schematic representation of the side view of an embodimentof the extraction apparatus of the present invention, illustrating thehigh-pressure chamber hereof, shown as a cylindrical vessel, into theinterior portion of which an inner sleeve having an opening at one endand into which dry ice may be placed, and a tapered end opposite theopen end at the end of which a collection vial is disposed, a porousinsert for holding plant material located within the cylinder, apressure lid adapted for maintaining pressure in the chamber and forproviding access to the feed insert and the collection vessel, and anexternal heating element.

FIG. 2 is a schematic representation of the side view of anotherembodiment of the extraction apparatus of the present invention,illustrating some common elements shown in FIG. 1 hereof, wherein theinner sleeve has a porous bottom adjacent to the porous material holder,including further, a siphon tube which extends to the bottom of theinterior portion of the chamber and connecting to the manual combinationpressure relief and discharge metering valve for directing fluid underpressure in the chamber through a detachable combination vaporizer andgas product separator, such that the extracted material is collected ina product collection vial, and the carbon dioxide gas is vented toatmosphere or collected.

FIG. 3 is a schematic representation of a side view of an embodiment ofa gas/product separation apparatus shown in FIG. 2 hereof adapted fordirect fluid communication with the pressure chamber, and illustrating amotorized flow metering valve.

FIG. 4 is a schematic representation of a side view of a thirdembodiment of the extraction apparatus of the present invention showinga gas/product separation apparatus integral with the high-pressurechamber and having a motorized flow metering valve, a chamber jacket forsupporting, heating and insulating the chamber and for permitting thechamber to be rotated manually or by utilizing a motor to improveextraction efficiency, wherein the material holder is located in avolume in the cap of the chamber, and the separation apparatus isdisposed on the bottom of the chamber, such that a siphon tube isunnecessary.

FIG. 5A is a schematic representation of a bottom view of the embodimentof the extraction apparatus shown in FIG. 4, hereof, while FIG. 5B is aschematic representation of a bottom sectional view of the embodiment ofthe extraction apparatus shown in FIG. 5A, hereof, with some of theparts having been relocated to improve understanding of the functioningof the combination vaporizer and gas product separator.

FIG. 6 is a schematic representation of cross section BB′ identified inFIG. 5A, hereof.

FIG. 7 is a schematic representation of cross section A-A′ identified inFIG. 5B hereof.

DETAILED DESCRIPTION

Briefly, the present invention includes an apparatus for extractingorganic compounds from plant materials using subcritical orsupercritical carbon dioxide. The apparatus has a sealable pressurechamber into which carbon dioxide dry ice and the plant materials areinserted, the pressure chamber, once sealed, self-pressurizing as thecontainer and contents are warmed to a chosen temperature, convertingthe solid CO₂ to liquid, or to a super-critical fluid as the temperatureand pressure rise above the Critical Point. The chamber can be rotatedwhen subcritical CO₂ liquid is employed to improve mixing between theliquid and the plant material. After a suitable extraction time, thecarbon dioxide solvent containing the extracted material may be ventedleaving extracts behind, or directed into a separator such that thecarbon dioxide and extracted material can be effectively separated.

In existing supercritical or subcritical carbon dioxide extractions, acertain quantity of viscous and waxy extracted materials may remain inthe chamber and valves after the carbon dioxide solvent is warmed,vaporized, and allowed to exit the chamber. These materials aredifficult to remove from the apparatus without the use of solvents orheat. This problem may be in part overcome with recirculating systems.However, in the present apparatus, the separator permits extractedmaterials to be separated from the carbon dioxide in an efficientmanner, with little extracted material remaining in the extractionchamber.

As stated above, subcritical/supercritical carbon dioxide possessesuseful properties as an extracting media for botanical and otherconstituents. In particular, the density of the carbon dioxide solventmay be varied to achieve selective separations by adjusting thetemperature and pressure of the carbon dioxide solvent.

Reference will now be made in detail to the present embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. In the FIGURES, similar structure will be identified usingidentical reference characters. It will be understood that the FIGURESare for the purpose of describing particular embodiments of theinvention and are not intended to limit the invention thereto. Turningnow to FIG. 1, a schematic representation of the side view of anembodiment of extraction apparatus, 10, of the present invention,illustrating high-pressure chamber or vessel, 12, shown as a cylindricalvessel having an open end, 14, reversibly sealed by pressure lid, 16.Removable cylindrical sleeve, 18, having an opening at one end, 20,disposed in the interior volume, 22, of chamber 12 has tapered portion,24, opposite open end 20 at the end of which removable collection vial,26, is located. Porous insert, 28, for holding plant or other materialto be processed is also disposed in chamber 12 within sleeve 18.Pressure lid 16 is adapted for maintaining pressure in chamber 12,utilizing O-ring seal, 30, and is removable for providing access to feedinsert 28 and sleeve 18 in chamber 12, by unscrewing threaded retainingring, 32. Clearly, there are many ways in which chamber 12 can bereversibly pressure sealed.

A chosen quantity of dry ice is placed in volume, 34, of chamber 12 forgenerating liquid carbon dioxide once sealed in the chamber. Externalheating element, 36, is operated by temperature controller, 38, andtemperatures internal to pressure vessel 12 are measured by temperaturesensor, 40. Combined pressure relief and vent valve, 42, and pressuresensor, 44, are utilized to control the pressure in chamber 12. Asmentioned hereinabove, subcritical carbon dioxide and supercriticalcarbon dioxide having chosen density can be generated by controlling thetemperature and pressure of chamber 12. Safety burst disk, 46, providessystem overpressure relief.

Base, 48, supports chamber 12 in an upright position. However, as willbe described hereinbelow, rotating or shaking chamber 12 may improveextraction efficiency and time.

FIG. 2 is a schematic representation of the side view of anotherembodiment of the extraction apparatus of the present invention,illustrating inner sleeve 18 having a porous bottom, 50, adjacent to theporous material holder 28, and siphon tube, 52, which extends to thebottom of the interior portion of chamber 12. Siphon tube 52 is in fluidcommunication with combination pressure relief and discharge meteringvalve 42, and directs fluid under pressure in chamber 12 through tube,54, to detachable combination vaporizer and gas product separator, 56,such that the extracted material is collected in product collection vial26 and the carbon dioxide gas is vented to the atmosphere through gasdischarge vent, 58, or collected. Separator 56 may be detachably mountedto flange, 60, integrally formed with or otherwise attached to pressurecap 16.

FIG. 3 is a schematic representation of a side view of a cycloneseparator embodiment of gas/product separation apparatus 56 shown inFIG. 2 hereof, adapted for direct fluid communication with chamber 12through inlet orifice, 62, formed in body, 64. Discharge valve 42 inFIG. 2 is replaced by flow metering valve, 66, driven by motor, 68, fordirecting fluid into vaporization chamber, 69, which leads intoseparator cylindrical inlet section, 70. Motor 68 is directed bycontroller, 71, with input from separator pressure sensor, 72, andseparator temperature sensor, 74. Heating element, 76, in heatingchamber is also operated by controller 71.

Pressure relief valve, 78, provides overpressure venting for chamber 12,and flushing/cleaning port, 78, provides access to fluid line, 82,through which metered fluid passes from chamber 12, passed heater 76, tocyclone separator, 84, which includes: collection vial, 26, havingcone-shaped interior, 86, and stand, 88, formed integrally therewith, orattached thereto, exhaust tube, 90, disposed longitudinally alongcenterline, 92, of vial 26, and in fluid communication with dischargevent tube, 94, cone-shaped separator hat, 96, disposed within vial 26supported by exhaust tube 90, and spaced-apart from open end, 98,thereof.

In operation, fluid from chamber 12 enters separator 56 through inlet62, which may be in fluid communication with tube 54 illustrated in FIG.2, or directly with chamber 12 as shown in FIG. 4, hereinbelow, the flowrate of the fluid being controlled by flow metering valve 66. Afterpassing through tube 82 the fluid flows over heating element 76, whereinsupercritical carbon dioxide and subcritical carbon dioxide liquidbearing extracted material is vaporized and the resulting gas streamwith the aerosol extracted materials is directed tangentially into thewide, upper portion of conical interior 86 of collection vessel 26.While spiraling downward toward the narrower portion of interior ofconical vessel 26, the aerosol materials in the gas stream driftradially outward due to centripetal force and are collected on conicalwall 86 of collection vessel 26. Less viscous constituents of thecollected material will flow downward along conical wall 86 under theinfluence of gravity and the downward component of the friction drag ofthe gas stream, past cyclone separator hat 96 and be collected in thelower cylindrical portion of vial 26. Heavier, more viscous constituentsof the collected materials will remain on conical walls 86. The carbondioxide gas stream will encounter cyclone separator hat 96 at the bottomof conical section 86, and be deflected upward to spiral through inletopening 98 of exhaust tube 90. The vaporized gas then passes theinterior of exhaust tube 90, and is vented to the atmosphere throughvent tube 94. Present separator 56 prevents extracted material fromremaining in chamber 12 and provides an effective separation from thecarbon dioxide solvent.

FIG. 4 is a schematic representation of a side view of a thirdembodiment of extraction apparatus 10 of the present invention showingan embodiment of gas/product separation apparatus, 56, integral withhigh-pressure chamber 12. Plant material container 28 is formed bypressure vessel cap 16 having wall, 100, which forms interior volume,102, and snap-in porous material cover, 104. O-ring 30 is disposed in acircumferential O-ring groove, 106, formed in the exterior surface, 108,of wall 100. Wall 100 also has a chosen number of outwardly facingbayonet attachment lugs, 110, for example 6 or 8, disposed on acircumference on outer surface 108 thereof, adapted for engagingcorresponding hooked bayonet slots, 112, formed in wall, 114, ofpressure vessel 12. Bayonet attachment spring, 116, generates a forcebetween cap 16 and chamber 12 for assisting the reversible seating ofattachment lugs 110 in slots 112. Spring 116 may be an elastomericspring. Separator 56 is shown attached to chamber 12, and will bedescribed in more detail hereinbelow.

Pressure Vessel assembly jacket, 118, which surrounds pressure vesselassembly, 119, and may be fabricated from metal or other sturdymaterial, has cylindrical interior surface, 120, onto which is attachedcylindrical insulating material, 122, adapted to receive chamber 12, andonto a portion of interior surface, 124, of which, heating element 36 isattached, whereby wall 114 of chamber 12 may be heated to a desiredtemperature. Cap insulation, 126, surrounds the exterior portion of cap16, and is adapted to slide into insulated jacket 118. Once assembled,chamber 12 and cap 16 may be slid into assembly jacket 118, which isattached by axle, 128, through rotary bearing, 130, supported by stand48, to motor, 132, for rotating jacket 118 during the extractionprocess.

Motor 132 and heating element 36, as well as the elements in separator56 are activated by controller, 134, through electrical connections,136, based on programmed input from the user and information gathered bythe sensors in separator 56, as will be explained in more detailhereinbelow.

FIG. 5A is a schematic representation of a bottom view of the embodimentof extraction apparatus 10 shown in FIG. 4, hereof, illustratingelements of separator 56 integral with bottom, 138, of chamber 12. Shownare chamber temperature sensor, 140, and chamber pressure sensor, 142,which are in fluid contact with chamber 12 through screened liquidoutlet, 144, not shown in FIG. 5A, and vaporization chamber temperaturesensor 74, and aerosol droplet size and velocity sensor, 146. Cycloneseparator member 84 is shown with conical product collection cup 26removed, illustrating cup sealing ring, 148, and tangential inlet jetopening, 150.

FIG. 5B is a schematic representation of a bottom sectional view of theembodiment of the extraction apparatus shown in FIG. 5A, hereof, withsome of the parts having been relocated to improve understanding of thefunctioning of the combination vaporizer and gas product separator.

FIG. 6 is a schematic representation of cross section B-B′ identified inFIG. 5A, hereof.

FIG. 7 is a schematic representation of cross section A-A′ identified inFIG. 5A hereof.

As stated, separator 56 separates the dissolved product from the liquidCO₂ solvent, and an integral pressure relief valve is provided withmanual vent valve 48 to protect pressure vessel 12 from overpressure,and allows manual depressurization of pressure vessel 12, if necessary.The elements of separator 56 may be integrated into pressure vessel 12or mounted separately, and accessed using external tubing, asillustrated in FIG. 2 hereof. Product collection vial 26, which may bedisposable, forms the lower cone of the cyclone separator 84.

Separator 56 may be operated automatically by process controller 134with several sequences being anticipated; that is, the order of thevarious steps may be varied depending on various circumstances.

Cap 16 is removed by pushing down on the cap against tension spring 116,turning the cap counter-clockwise until attachment lugs 106 cleardetents 112. The lug and detent combination prevents cap 16 fromrotating when pressure vessel 12 is pressurized, and separating the capfrom the pressure vessel body. Once the cap is removed, snap-in feedstock chamber porous retaining cover 104 is removed by pulling the coverout over spring detents, not shown in FIG. 4. The material to beprocessed is placed in the chamber and the cover is snapped into place.Open cavity 34 of pressure vessel is then filled with a chosen quantityof carbon dioxide dry ice, and the cap is reattached to the pressurevessel by pushing down on the cap and turning the cap clockwise past thedetents until the attachment lugs seat in their sockets.

Turning to FIGS. 4-7, the initial conditions and position for chargingextraction apparatus 10, are that pressure vessel 12 is empty, atatmospheric pressure and room temperature, and vertically or nearvertically oriented by motor 132 for charging, wherein cap/feed stockmaterial chamber 16 is uppermost. Vaporization heater 76 is off, manualvent valve 48, if present, is closed, and motorized liquid flow meteringvalve 66 is open. Product collection vial 26 is installed on gas/oilseparator 56 on the lower part of pressure vessel 12. After fillinginterior volume 102 with botanical material, replacing snap-in porousmaterial cover 104, filling pressure vessel 12 with carbon dioxide dryice, and sliding and latching cap 16 into pressure vessel 12, pressurevessel assembly 119 is rotated such that cap 16 is below vessel 12, andthe motorized flow metering valve 66 is left open for betweenapproximately 15 s and about 30 s, to vent the air displaced by theheavier CO₂ from the pressure vessel. Motorized flow metering valve 66is then closed and kept closed until the pressure vessel is againrotated to the charge position at the end of the processing cycle. Notethat flow metering valve 66 is a positive shutoff valve. Pressure vesselheating element 36 may be activated at this time to pressurize thevessel, whereby liquid CO₂ or supercritical CO₂ is formed, depending onthe temperature and pressure attained in pressure vessel 12.

During processing, the pressure vessel assembly 119 may be oscillatedone or more times between the charge and processing positions bycontroller 134 to increase extraction efficiency by mixing any liquidcarbon dioxide with the botanical material. Such oscillation may not berequired if supercritical CO₂ is utilized for the extraction. Ingeneral, the solubility of a substance in a dense gas, such as asupercritical fluid, increases as the density increases as a function oftemperature and pressure. Therefore, as the temperature/pressure of thesupercritical fluid is reduced, a phase separation occurs with denseliquid containing the bulk of the extract and the gas containing verylittle. Droplets of supersaturated liquid could then be formed as aresult of this process. If this such droplets occur within the feedstock material or on the side walls of the chamber, some of the extractmay be deposited. Thus, “rinsing” the feedstock material and the chamberwalls after a supercritical extraction and prior to separating theproduct from the liquid CO₂ may be beneficial.

After a chosen processing time, the separation cycle begins, whereincontroller 134 directs vaporization heater 76 to preheat vaporizationchamber, 69, until a specified temperature is reached, then slowly opensliquid flow metering valve 66, to adjust the flow rate, whereby thespecified temperature is maintained in the vaporization chamber. Tooptimize the efficiency of separator 56, controller 134 may also be usedto adjust the temperature and flow rate through vaporization chamber 69,such that the velocity and droplet size sensed by aerosol droplet sizeand velocity sensor 146 most closely matches the design parameters forseparator 56 to maximize the separation efficiency and minimize the timefor performing the separation process.

A cyclone separator relies on the force from the centripetalacceleration of the entrained particle/aerosol mass to overcomeaerodynamic drag and any turbulence present in the gas stream.Therefore, measuring the particle size and velocity provides informationto regulate the liquid flow into the vaporizer to prevent turbulence andto optimize the extraction efficiency of the cyclone separator. Thevolume of liquid being converted into gas will influence the gas streamvelocity, the entrained aerosol velocity (typically less than the gasstream velocity), and the resulting aerosol droplet size (probablysmaller). In general, the smaller the droplet size the greater thesurface area to volume ratio, and the lower the radial terminal velocityinduced by centripetal acceleration. Lower radial terminal velocitiesrequire longer residence time for the droplets to migrate to the outerwalls of the cyclone cone. Increasing gas stream velocity will bothincrease the aerosol droplet velocity and the associated centripetalacceleration, but will decrease the residence time and may introduceturbulence, which may decrease separation efficiency. Decreasing theliquid flow into the vaporizer will lower the gas stream velocity,increase residence time, and probably increase aerosol size, but willdecrease centripetal acceleration. Thus, the optimum liquid flow rate isa complex optimization problem that depends on the properties of theaerosol droplets, the geometry of the cyclone separator, the velocity ofthe gas stream and particles, and the particle size. Information fromthe particle size and velocity sensor is necessary, but not sufficient,for making the calculations for an optimization feedback loop.

When the CO₂ liquid is exhausted from pressure vessel 12, thetemperature of vaporization chamber 69 will begin to rise and liquidflow metering valve 66 is fully opened by controller 134 using motorservo motor 68. Full opening of the liquid flow metering valve andreduction of the pressure in the pressure vessel to atmospheric pressuresignals the completion of the separation cycle, and vaporization heater76 is de-energized, liquid flow metering valve 66 remaining open. If thepressure in pressure vessel 12 does not return to atmospheric pressurebetween approximately 1 and about 2 min., an error signal is generated.Once an error signal is generated, an operator must reduce the residualpressure in pressure vessel 12 using manual vent valve 48 to at or nearatmospheric pressure before the pressure vessel can be opened, becausehigher residual pressure in pressure vessel 12 will prevent the bayonetattachment lugs 106 on the cap from being rotated past the detents inpressure vessel bayonet slots 112.

After removal of the expended biomaterial, apparatus 10 is ready foranother extraction/separation. Cone vial 26 may be detached foraccessing the extracted material, and replaced with a new vial, ifdesired.

Having generally described the apparatus and method, the followingEXAMPLE provide additional details.

EXAMPLE

Chamber 12 may develop significant pressures if the carbon dioxideliquid volume is greater than that of the chamber as carbon dioxidepasses through the subcritical liquid state on the way to thesupercritical state. Calculations on the sizing and charging of pressurevessels for preventing the vessels from being completely filled with CO₂liquid and becoming over-pressurized, follow, assuming a factor ofsafety (FOS) of 1.25 (note that 1.15 is the minimum FOS used for mostengineering projects), a minimum CO₂ liquid density of ρ_(CO2Lmin)=0.680kg/l @ ˜30° C. and 80 bar (1,180 psi); and a solid density ofρ_(CO2Lmin)=1.562 kg/l @ ˜78.5° C. and 1 bar. Assuming further a typicalBotanical or Plant Material Density for cannabis plants of ρ_(B)=0.312kg/l; a THC solubility, S_(CO2)=0.3%; a THC extraction percentage,η_(ρ)=12%, and a mass ratio of dry ice to botanical material, R_(m)=40kg of CO₂/kg of Botanical Material (extraction percentage of THC in thebotanical material, 12%, (Units of kg[THC]/kg[botanical material])divided by THC solubility in CO2, 0.03% (Units of kg[THC]/kg[CO2]);leaving units of kg[CO2]/kg[botanical material]), and the pressurevessel charge volumes per kilogram of Botanical material, including theFOS are:

V_(BM)=3.21 l; Volume of botanical material;

V_(DI)=25.62 l; Volume of solid CO₂ (dry ice);

V_(HS)=41.52 l; Volume of required head space (with FOS); and

V_(tot)=70.3 l; Total Volume, from which the Percentage Charge Volumes(Including FOS) are:

V_(%BM)=4.6%; Percentage volume of botanical material;

V_(%DI)=36.4%; Percentage volume solid CO2 (dry ice); and

V_(%HS)=59.0%; Percent volume of required head space (with FOS).

-   For a 1 l pressure vessel, the mass of botanical material is 14 g;    the mass of dry ice is 569 g; and the mass of product is 2 g.

The foregoing description of the invention has been presented forpurposes of illustration and description and is not intended to beexhaustive or to limit the invention to the precise form disclosed, andobviously many modifications and variations are possible in light of theabove teaching. The embodiments were chosen and described in order tobest explain the principles of the invention and its practicalapplication to thereby enable others skilled in the art to best utilizethe invention in various embodiments and with various modifications asare suited to the particular use contemplated. It is intended that thescope of the invention be defined by the claims appended hereto.

What is claimed is:
 1. An apparatus for extracting organic compoundsfrom plant material, comprising: a chamber capable of being pressurized;a pressure lid for providing a gas-tight seal for the opening, and formaintaining a chosen pressure within said chamber; a collection vial; aremovable sleeve disposed in said chamber having an opening at one endfor receiving solid carbon dioxide, and a tapered portion opposite theopen end adapted to receive said collection vial; a first heatingelement adapted for heating said chamber; a temperature sensor; apressure sensor; a porous container adapted to be placed in said sleevefor holding the plant material and for permitting the plant material tobe contacted by liquid carbon dioxide or supercritical carbon dioxide;and a vent valve for permitting gaseous carbon dioxide to exit saidchamber.
 2. The apparatus of claim 1, further comprising: a supporthaving an interior portion adapted for receiving and holding saidchamber, and an exterior portion; an axle attached to the exteriorportion of said support; a rotary bearing adapted to receive said axle;and a stand adapted for supporting said rotary bearing into which saidaxle is inserted; whereby said support bearing said chamber is rotated.3. An apparatus for extracting organic compounds from plant material,comprising: a chamber capable of being pressurized having an opening; apressure lid for providing a gas-tight seal for the opening, and formaintaining a chosen pressure within said chamber; a collection vial; aremovable sleeve disposed in said chamber having an opening at one endfor receiving solid carbon dioxide, and a tapered portion opposite theopen end, adapted to receive said collection vial; a first heatingelement adapted for heating said chamber; a temperature sensor; apressure sensor; a porous container adapted to be placed in said sleevefor holding the plant material and for permitting the plant material tobe contacted by liquid carbon dioxide and supercritical carbon dioxide;a vent valve for permitting carbon dioxide and supercritical carbondioxide the chamber.
 4. The apparatus of claim 3, further comprising: asupport having an interior portion adapted for receiving and holdingsaid chamber, and an exterior portion; an axle attached to the exteriorportion of said support; a rotary bearing adapted to receive said axle;and a stand adapted for supporting said rotary bearing into which saidaxle is inserted; whereby said support bearing said chamber is rotated.5. A method for extracting organic compounds from plant material,comprising: placing a chosen quantity of solid carbon dioxide and aselected quantity of plant material into a chamber capable of beingpressurized; heating the chamber to a temperature and pressure such thatliquid carbon dioxide or supercritical carbon dioxide forms in thechamber; permitting the liquid carbon dioxide or the supercriticalcarbon dioxide to contact the plant material for a chosen period oftime, whereby organic compounds are extracted from the plant material,forming thereby a solution of the extracted plant material in liquidcarbon dioxide or supercritical carbon dioxide; separating the extractedmaterial from the liquid carbon dioxide solution or supercritical carbondioxide solution by permitting the carbon dioxide to exit the chamber,leaving the extracted material to condense in the chamber.
 6. The methodof claim 5, further comprising the step of removing residual air fromthe chamber subsequent to said step of placing a chosen quantity ofsolid carbon dioxide and a selected quantity of plant material into thechamber.
 7. The method of claim 5, wherein the density of the liquidcarbon dioxide or the supercritical carbon dioxide is changed by varyingthe pressure and temperature of the liquid carbon dioxide or thesupercritical carbon dioxide, whereby the solubility of certain of theorganic compounds to be extracted in the liquid carbon dioxide or thesupercritical carbon dioxide is changed.
 8. The method of claim 5wherein the extraction is performed in the absence of chemicals otherthan carbon dioxide.
 9. A method for extracting organic compounds fromplant material, comprising: placing a chosen quantity of solid carbondioxide and a selected quantity of plant material into a chamber capableof being pressurized; heating the chamber to a temperature and pressuresuch that liquid carbon dioxide and supercritical carbon dioxide formsin the chamber; permitting the liquid carbon dioxide and thesupercritical carbon dioxide to contact the plant material for a chosenperiod of time, whereby organic compounds are extracted from the plantmaterial, forming thereby a solution of the extracted plant material insubcritical liquid carbon dioxide and supercritical carbon dioxide;separating the extracted material from the liquid carbon dioxidesolution and supercritical carbon dioxide solution by permitting thecarbon dioxide to exit the chamber, leaving the extracted material tocondense in the chamber.
 10. The method of claim 9, further comprisingthe step of removing residual air from the chamber subsequent to saidstep of placing a chosen quantity of solid carbon dioxide and a selectedquantity of plant material into the chamber.
 11. The method of claim 9,wherein the density of the liquid carbon dioxide and the supercriticalcarbon dioxide are changed by varying the pressure and temperature ofthe liquid carbon dioxide and the supercritical carbon dioxide, wherebythe solubility of certain of the organic compounds to be extracted inthe liquid carbon dioxide or the supercritical carbon dioxide ischanged.
 12. The method of claim 9, wherein the extraction is performedin the absence of chemicals other than carbon dioxide.